Use of Extrapolation in New Drug Approvals By the US Food and Drug Administration

Among 105 novel drug approvals from 2015 to 2017, extrapolation of pivotal trial data to broader patient populations occurred in 21 drugs (20%), with disease severity being the most common basis for extrapolation, followed by disease subtype and concomitant medication use. While such extrapolations may be clinically reasonable, they reduce indication generalizability and necessitate enhanced postapproval monitoring by the FDA to detect unanticipated safety issues or effectiveness differences in real-world use.